The greatest obstacle to obtaining optimum efficiency in streamlining a fuselage is surface friction. This can be in several forms but typically is one of or a combination of boundary layer drag, skin friction, viscosity, surface tension, cavitation and turbulence.
Existing technologies seek to reduce this drag and optimise the energy efficiency of a moving body or fuselage by altering its surface to be as smooth as possible with the least possible protuberances or alternatively to roughen the smooth surface or to give it a rippling surface similar to that of a shark, dolphin or golf ball.
The objective is to minimise the effects of drag from fluids flowing past.
Another attempt to cut drag has included the fitting of small vortex generators to wings and other parts of the fuselage.
A further attempt has been to fit a spike-like protuberance extending forwardly in the direction of travel of the fuselage through the fluid.
In general, it has been an objective of these attempts to maintain straight, laminar flow over the body of the fuselage, and to suppress separation or turbulence as far as is possible. Alternatively, through the use of dimpled or roughen surfaces and vortex generators, the objective has been to create myriad eddies in close proximity to the fuselage surface to break up the boundary layer.
Essentially, all these approaches are designed to assist fluids slide past the body with a minimum of friction.